David Crosby performed a set at The Birchmere in Alexandria, Virginia on June 4, 2019. (Michael Robinson Chavez/The Washington Post)

Not that many years ago, David Crosby would have been a top seed in any bracket of ’60s rockers least likely to still be breathing, let alone rocking, in 2019. But there he was doing both at the Birchmere on Tuesday, at age 77, wowing fans with a two-set show spanning a career that was worth reliving all the way through.

Crosby, backed by a showy and capable quartet, began the set with influential, harmony-laden classics (and seminal wimp rock) from his days with Crosby, Stills & Nash and sometimes Young — songs such as “Guinevere” and “The Lee Shore” and “Deja Vu.” Crosby also offered up Joni Mitchell’s “For Free,” a pretty waltz previously recorded by his first famous band, the Byrds, for a 1973 reunion LP.

His ability to rock out was somewhat crimped on this night, because his band’s regular drummer, Steve DiStanislao, was forced to suddenly leave the tour due to a death in the family; a kit sat empty for the first half of the night But Crosby promised, at the top of the show, “We absolutely need to play rock-and-roll at some point!” And after an intermission (before which Crosby advised the crowd to “go to the parking lot and smoke a joint”), he made good on that promise. Kevin O’Connor, normally a roadie for the band, sat in DiStanislao’s throne for “Wooden Ships,” “Long Time Gone,” and “Almost Cut My Hair” — all delivered as extended jams and received with standing ovations. Crosby watched each of his bandmates go through their solos. After so many years, and so many casting changes, he was still in love with being in a band.

Crosby’s attachments have not always been so benign. His rap sheet for drug-related offenses over the past several decades is about as hefty as his discography. There was a 1982 conviction for heroin and cocaine possession, plus gun offenses. He got busted in 1985 for fleeing the scene of an accident, after which cops found cocaine and an illegally concealed weapon in his car. Crosby spent time in the clink again when a suitcase he left behind at his hotel was found to contain (yawn) illegal drugs and guns. There were also tabloid chapters that had him as the sperm donor for Melissa Etheridge’s “test-tube” baby, and that time Phil Collins paid for a new liver to replace the one Crosby had ruined through years of chemical abuse.

The fact of his survival, lucky as he was, has had an ennobling effect on Crosby’s checkered past. The drugs, the guns, the organ failure — it’s all safely part of the story now. Onstage, at the Birchmere, Crosby appeared almost beatific: a living, breathing rebuttal to the “Just Say No” scolds of yesteryear. His voice was as strong as ever. His beautiful white hair flowed beneath a red knit cap he said his wife made for him. He looked like the coolest grandpa imaginable.

And yet a specter of mortality hung over the show. Crosby has been thinking, and singing, about death since he was a young pacifist. Before an a cappella version of “What Are Their Names?” Crosby explained that he had written the anti-military-industrial-complex song when he was a kid, and performs it at every show. “It’s done no good at all,” he said. “Things are worse now than when I wrote it.”

But Crosby is still breathing, and he hasn’t given up hope. Near the end of the night, he brought O’Connor out one last time for a thrilling version of “Ohio,” Neil Young’s ode to the Kent State University students slaughtered by National Guard troops in 1970. “If you sing it well,” he told the crowd, “things may change.”

As Crosby rocked, they sang it well.